Spirometry & Asthma: The Basics. Beth Allen, MD, Partners for Kids Kim Spoonhower, MD, Ohio AAP

Transcription

1 Spirometry & Asthma: The Basics Beth Allen, MD, Partners for Kids Kim Spoonhower, MD, Ohio AAP 1

2 CME Disclosure Statement We have no relevant financial relationships with the manufacturers(s) of any commercial products(s) and/or provider of commercial services discussed in this CME activity. We do not intend to discuss an unapproved/investigative use of a commercial product/device in our presentation. 2

3 Overview Role of spirometry in asthma Spirometry What it is Basic components of interpretation Spirometry in children Quality issues Options for getting spirometry done

4 Asthma & Spirometry: Diagnosis Reversible airway obstruction a key feature of asthma Spirometry potential proof of disease Normal baseline spirometry does not rule out asthma

5 Asthma & Spirometry: Management Severity class at diagnosis (FEV1% pred) Monitoring control (FEV1% personal best) Detection of significant dysfunction in asymptomatic patients Recommended yearly

6 Spirometry Priority Patients Diagnosis not entirely clear (to doc or parents) caveat: PFT s can rule in asthma, they don t rule it out Child who gets sick so quick or with recurrent severe episodes caveat: baseline well function may be a lot worse than you think/patient recognizes Teenagers eager to wean off meds, or anyone that might be minimizing symptoms Patients not responding to entry level controller therapies

7 Spirometry the Maneuver Three phases: Maximal inspiration Blast of exhalation Continued exhalation to the end of test

8 Spirometry What it Does Measures volume and speed of maximal expiratory effort Detects abnormal flow Detects rapid changes in airway caliber Assesses changes in function over times

9 Spirometry Key Values FVC = Forced Vital Capacity* FEV1 = Forced Expiratory Volume in the first second* FEV1/FVC = Ratio of above (FEF25 75 = Average rate of flow at mid exhalation*) * Expressed as % predicted

10 % Predicted: Comparison to Normals

11 Steps of Interpretation Is there anything wrong? What type of wrongness? How bad is it? Pre and post testing any change? Do the loops fit? Quality?

12 Is There Anything Wrong? FVC < 80% of predicted* FEV1 < 80% of predicted* FEV1/FVC ratio < 80 % (actual value)* (FEF < 60% of predicted) * In adults 75%

13 What Kind of Wrongness? Obstruction Involves a flow problem ASTHMA Typically a problem within the airways Restriction Involves a volume problem Typically involves a problem anywhere else!

14 Spirometry and Disease Type Obstruction Restriction FVC Nl or FEV 1 FEV 1 /FVC < 80 (75) % > 80 (75)% FEF ** ** Confirm by TLC measurement

15 Spirometry: Interpretation < 80 FEV1/FVC 80 Normal or elevated Airflow Obstruction FEV1 Classify severity of airflow obstruction FEV1 >70% Mild FEV % Moderate FEV % Moderately severe FEV % Severe FEV1 < 35% Very severe Normal FEV1 % >80% and FVC%> 80% Abnormal FEV1 < 80% and FVC <80% Formal pulmonary function testing with lung volumes Restriction or Air trapping

16 Pre and Post Testing: Any Change? Reversibility Characteristic of Asthma Rapid increase or decrease in function following medication, or in response to trigger Significant change FVC or FEV1 change of 12% FEF change of 20%

17 Patient Example FVC 99% FEV1 91% FEV1/FVC 75.7 % FEF % Something wrong? What kind? How bad? Any change? Change after bronchodilator FEV1 19% increase FEF % increase

18 Does the Loop Fit? Obstruction Restriction Flow Flow Volume Volume

19 Progressive Obstruction Normal Mild Mod Severe

20 (+) Bronchodilator Test Baseline Post Albuterol 18% improvement FEV1

21 Assessing Testing Quality People factors Components of a good test Results: Quality criteria

22 Not Every Patient Can Perform a Reliable PFT

23 Great Coaches Needed Correct posture Avoid leaks Nose clips Lips sealed on mouthpiece Avoid occlusion by tongue Rapid inhalation Start exhalation within 1 sec Cheerleading to finish!

24 Quality Killers Valsalva manuever (glottic closure) or hesitation causing stop in airflow Leak at mouth Tongue or teeth obstructing mouthpiece Cough during maneuver Early cut off Lack of maximal effort throughout

25 Special Tips for Kid Spirometry Kid friendly technicians Bright, pleasant atmosphere Encouragement & praise Avoid scolding/intimidation Visual feedback (kid software) May need practice sessions

26 Results: Quality Criteria Within maneuver criteria Between maneuver criteria

27 Tongue Obstructing Mouthpiece Flow Volume

28 Slow Rise Flow Volume

29 Glottic Closure (Cough) Flow Volume

30 Incomplete Exhalation Flow Volume

31 Why Complete Exhalation Matters Flow FVC Volume

32 Adequate exhalation criteria: Volume Time Curve The volume time curve shows no change in volume for 1 sec Patient has tried to exhale 3 secs (if < 10 years old) 6 sec (if > 10 years) Volume Time

33 Between Maneuver Evaluation Minimum 3 satisfactory maneuvers Two largest FVC s within 0.25 L Two largest FEV1 s within 0.15 L Flow volume loops overlap Up to 8 attempts reasonable

34 Spirometry Options/Challenges In Office Equipment and space requirements Personnel requirements Training requirements Scheduling Quality assurance of testing & interpretation Billing Outside Referral Logistics of ordering Patient compliance (actually going to test) Delayed results

35 Spirometry Equipment Options

36 PC based Spirometers Sensor (pneumotach) connects to computer Software package installed on computer Graphic displays of flow volume loops, volume time curves Some able to trend tests over time Pediatric incentive graphics available* Printable when connected to network/printer Some software systems able to communicate directly with EMR*

37 PC based spirometers Specific Brands Welch Allyn ndd Medical Technologies Viasys

38 Hand held Spirometers Stand alone, no computer required Many can be connected to PC Variable displays, +/ flow volume curve Some have pediatric incentives Some do not require calibration Extremely portable Printing Some have built in printing capability Some can connect to PC for printing

39 Hand held Spirometers Specific Brands Welch Allyn ndd Medical Technologies MIR

40 Summary: PFT s in Asthma Often normal even in uncontrolled patients When ABNORMAL they can help 1. Confirm dx 2. Identify level of illness not expected from symptom report 3. Assist with tracking response to therapy changes 4. Alert you that the diagnosis isn t asthma... Are NOT helpful if they contain bad data either from poor test or poor interpretation Recommended yearly & prn

41 Case #1: History 7 year old boy who gets winded quickly when he plays soccer. He s had bronchitis 3 times in the past year Physical exam: normal.

42

43 Case # 2 16 year old with longstanding asthma Quit taking his controller medication since last visit Says he feels fine

44

45 Case #3: History 6 year old with 2 month long chronic cough. Varies wet to dry. Coughs more at night than during the day. Family history of allergy No meds tried yet Exam and CXR normal

46

47 Oh Wait Those were the wrong PFT s for this kid Here are the real PFT s...

48

49 Case #4 13 year old with h/o intermittent wheezing with colds Now reporting wheeze and dypsnea walking up stairs Symptoms worsened since he was in a severe car vs pedestrian MVA (intubated at scene, etc.)

50 Case #4: Spirometry Baseline FVC 68% FEV1 29% FEV1/FVC 36.4% FEF % Post bronchodilator 80% (18% change) 36% (25% change) 27% (19% change)

51 Case #4: Flow Volume Curve

52 Case #4 Bronchscopy

53 Case #4: Post Surgery FVC 99% FEV1 89% FEV1/FVC FEF % No significant change post bronchodilator

54 Questions?